1. Field of the Invention
The present invention relates to a magnetic head, and more particularly to a magnetic head comprising a pair of core halves and one or more thin magnetic metal layers attached to each side surface of the core half facings to provide the magnetic gap between the core halves.
2. Description of the Prior Art
A conventional magnetic head of the above type is shown in FIG. 1, wherein the magnetic head is comprised of a first core half 1, a second core half 2 and a coil winding (not shown) wound across coil winding opening 3 defined in the first core half 1. Said first core half 1 is comprised of a first core base 4 and a first magnetic thin layer 6 made of metallic magnetic material having a high saturation magnetic flux density and fitted on the side surface of the first core base 4 opposing to a magnetic gap 5. Said second core half 2 is also comprised of a second core base 7 and a second magnetic thin layer 8 made of metallic magnetic material having a high saturation magnetic flux density and fitted on the side surface of the second core base 7. In the prior art, in order to define the magnetic gap length of smaller than 0.5 .mu.m, each of the surfaces of the first and second core halves 1 and 2 which form the magnetic head gap 5 is coated by SiO.sub.2 material, while the other parts of both core halves 1 and 2 are connected by means of plastic resin or glass of low temperature melting glass.
However, the opposing surfaces of the halves defining the magnetic gap 5 are covered only by the magnetic thin layers 6 and 8 and SiO.sub.2 layer. Therefore the opposing surfaces are basically not mechanically bonded, but the geometrical relation of both opposing surface to define the magnetic gap is kept only by the bonding of the plastic resin materials or low temperature melting materials present in the parts of the first and second halves 1 and 2, other than the magnetic gap 5. Therefore, in the process of grinding the sliding surface of the magnetic head on which the magnetic recording medium slides, the SiO.sub.2 layer tends to be separated from the connecting surfaces, whereby there is a disadvantage in that a correct gap length at the magnetic gap 5 can not be obtained.
Another conventional way of bonding the opposing surfaces is to form a glass thin layer by sputtering or vacuum evaporation in the region of the opposing surfaces of the magnetic gap 5, then melting the glass under 700.degree. to 800.degree. C. However, in case amorphous magnetic alloy is used for the magnetic thin layers 6 and 8, the amorphous magnetic alloy is crystallized, thereby resulting in lowering the magnetic characteristic of the magnetic head. On the other hand, in case the low temperature melting glass is used for bonding the core halves 1 and 2, there is a tendency for a chemical reaction to occur between the low temperature melting glass and the amorphous magnetic alloy of the magnetic thin layers 6 and 8, thereby lowering the magnetic characteristic of the magnetic head.